2019 Mercedes-AMG GT C Coupe

2019 Mercedes-AMG GT C Coupe

This story has been updated with C/D test results. Think of the GT C that has been added to the Mercedes-AMG GT lineup as the equivalent of the Carrera GTS in the Porsche 911 roster. Both cars are the third step up on the power and expense ladder. Both come standard with distinctive interior and exterior design details. Both have fatter rear haunches to accommodate wider wheels and an increase in track compared with their lesser brethren. And both are topped by a track-oriented model further up the price and power scale鈥攖he GT R in the AMG's case and the GT3 for the Porsche. Although AMG has copied the model structure that Porsche has successfully developed over more than 50 years of the 911, it does so with a completely different sort of car. The GT has its engine in the front rather than in the rear. That engine is a twin-turbocharged 4.0-liter V-8, not a twin-turbo 3.0-liter flat-six. And instead of the 911's clean and classic lines, the GT snaps and crackles with visual firepower.

In this latest C variant of the GT, that muscularity is enhanced from the rear view by an increase in overall width from 76.3 to 79.0 inches. The GT C's engine also has more in common with the GT R's than with the one in the base and S versions of the GT. The slightly different version of the 4.0-liter V-8 in the C and the R is fitted with larger turbochargers to develop even higher boost pressure more efficiently. To help in this task, they employ freer-flowing exhaust ports, larger heat exchangers for the liquid-to-air intercoolers, and a reduced compression ratio鈥?.5:1 instead of 10.5:1 on the less powerful engines. Operating with a peak boost of 18.1 psi, the GT C engine produces 550 horsepower at 6250 rpm and 502 lb-ft at 1900 rpm. The R engine runs 19.6 psi to develop 577 horses and 516 lb-ft. The seven-speed dual-clutch automatic transmission comes in two versions to match these engines. The lower-powered cars get a wider-ratio gearbox coupled to a 3.67:1 final drive, while the C and R transmissions have a higher first and a lower seventh gear attached to a 3.88:1 rear end.

That produces an overall ratio spread that's about as close as that of the seven-speed dual-clutch in the 911 GT3. First gear is about 5 percent taller than in the standard AMG GT's gearbox, second through sixth are 5 percent shorter, and seventh is almost 14 percent shorter. The C and R models also get standard electronically controlled engine and transaxle mounts to provide a better combination of comfort and precision than can be achieved with conventional mounts. Between the added power and the shorter gearing, the GT C is notably more energetic than the hardly slow base and S versions. Driving on the back roads of northern Germany near Bad Driburg, the C model leaps ahead when you squeeze the accelerator and kicks down less often than its brethren. Even if you put the gearbox in manual mode and leave it in top gear, there's still plenty of grunt.

Throttle response is also prompt, with notably less turbo lag than in a modern 911 at low rpm. Back home on our test track, we strapped our test gear to the GT C. Despite the wide rubber, we found the rear tires still struggled for purchase during launch-control starts. Ultimately, we achieved a 3.5-second zero-to-60-mph time and clobbered the quarter-mile in 11.5 seconds with a trap speed of 128 mph; staying on the throttle for an additional five seconds brings up the 150-mph mark. That's quick, but the GT C's arch nemesis, the Porsche 911 GTS PDK, rockets to 60 mph in 3.0 seconds and through the quarter in 11.3 seconds with a trap speed of 125 mph. As hinted at by its faster trap speed, the GT C begins to build serious steam as the speeds climb, beating the 911 to the 150 mph mark by 0.9 second. Although these AMG GTs weigh several hundred pounds more than equivalent Porsches, they have a similarly responsive and lively character. Steering feel is excellent thanks to the electrohydraulic steering rack.